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STP85NF55 N-Channel MOSFET Equivalent & Substitute Parts
Part Overview
The STP85NF55 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 55V drain-to-source voltage and 80A continuous drain current at 25°C. This device is packaged in TO-220-3 through-hole configuration and is part of the STripFET™ II series. The part is currently listed as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and production continuity. Substitute parts must maintain compatibility across critical electrical parameters including voltage rating, current capacity, on-resistance characteristics, and thermal performance while preserving the through-hole TO-220 mounting interface.
Substiute Parts
Key Parameters
| Parameter | Value | Unit | Condition |
|---|---|---|---|
| Drain-to-Source Voltage (Vdss) | 55 | V | Maximum rating |
| Continuous Drain Current (Id) | 80 | A | @ 25°C (Tc) |
| On-Resistance (Rds On) | 8 | mOhm | @ 40A, 10V Vgs |
| Gate Threshold Voltage (Vgs(th)) | 4 | V | @ 250µA |
| Gate Charge (Qg) | 150 | nC | @ 10V Vgs |
| Power Dissipation | 300 | W | @ Tc |
| Operating Temperature Range | -55 to 175 | °C | Junction temperature (TJ) |
| Package Type | TO-220-3 | — | Through-hole |
| RoHS Status | ROHS3 Compliant | — | — |
Substitute Part Grouping Explanation
Substitution of the STP85NF55 is determined by the following critical parameters:
Voltage Compatibility: Substitute parts must have a Vdss rating equal to or greater than 55V. Parts rated at 60V or 75V are acceptable as they provide equivalent or enhanced voltage margin.
Current Capacity: The continuous drain current (Id) at 25°C must be equal to or exceed 80A (Tc). Parts rated at 75A, 80A, 100A, or 140A satisfy this requirement.
On-Resistance (Rds On): The maximum on-resistance specification must be compatible with the application's thermal and efficiency requirements. The STP85NF55 specifies 8mOhm @ 40A, 10V. Substitute parts with Rds On values between 6mOhm and 19mOhm are functionally equivalent within typical application tolerances.
Gate Characteristics: Gate threshold voltage (Vgs(th)) and gate charge (Qg) must be within compatible ranges. The STP85NF55 specifies 4V threshold and 150nC gate charge. Substitute parts with 2.5V to 4V threshold and 30nC to 275nC gate charge are acceptable.
Thermal Performance: Power dissipation capability must support the application. The STP85NF55 is rated at 300W (Tc). Substitute parts rated at 75W to 330W are functionally equivalent.
Package and Mounting: All substitute parts must use TO-220-3 through-hole packaging to ensure mechanical and electrical compatibility with existing PCB layouts and thermal management solutions.
Compliance: All substitute parts must maintain ROHS3 compliance and REACH unaffected status to meet regulatory requirements.
Parameter Comparison
| Part Number | Manufacturer | Vdss (V) | Id @ 25°C (A) | Rds On (mOhm) | Vgs(th) (V) | Qg (nC) | Power Dissipation (W) | Operating Temp (°C) | Status |
|---|---|---|---|---|---|---|---|---|---|
| STP85NF55 | STMicroelectronics | 55 | 80 | 8 @ 40A, 10V | 4 @ 250µA | 150 @ 10V | 300 | -55 to 175 | Obsolete |
| AOT2610L | Alpha & Omega Semiconductor | 60 | 55 | 10.7 @ 20A, 10V | 2.5 @ 250µA | 30 @ 10V | 75 | -55 to 175 | Active |
| AOT470 | Alpha & Omega Semiconductor | 75 | 100 | 10.5 @ 30A, 10V | 4 @ 250µA | 136 @ 10V | 268 | -55 to 175 | Active |
| AUIRF3205Z | Infineon Technologies | 55 | 75 | 6.5 @ 66A, 10V | 4 @ 250µA | 110 @ 10V | 170 | -55 to 175 | Not For New Designs |
| AUIRF3305 | Infineon Technologies | 55 | 140 | 8 @ 75A, 10V | 4 @ 250µA | 150 @ 10V | 330 | -55 to 175 | Obsolete |
| FDP75N08A | onsemi | 75 | 75 | 11 @ 37.5A, 10V | 4 @ 250µA | 104 @ 10V | 137 | -55 to 150 | Obsolete |
| HUF75332P3 | onsemi | 55 | 60 | 19 @ 60A, 10V | 4 @ 250µA | 85 @ 20V | 145 | -55 to 175 | Active |
| HUF75339P3 | onsemi | 55 | 75 | 12 @ 75A, 10V | 4 @ 250µA | 130 @ 20V | 200 | -55 to 175 | Active |
| HUF75344P3 | onsemi | 55 | 75 | 8 @ 75A, 10V | 4 @ 250µA | 210 @ 20V | 285 | -55 to 175 | Active |
| HUF75345P3 | onsemi | 55 | 75 | 7 @ 75A, 10V | 4 @ 250µA | 275 @ 20V | 325 | -55 to 175 | Active |
| IPP80N06S207AKSA1 | Infineon Technologies | 55 | 80 | 6.6 @ 68A, 10V | 4 @ 180µA | 110 @ 10V | 250 | -55 to 175 | Discontinued at DiGi Electronics |
Engineering Selection Recommendations
Primary Substitutes (Active Status, Full Compatibility):
The HUF75344P3 and HUF75345P3 from onsemi are recommended as primary substitutes. Both devices maintain the 55V Vdss rating, support 75A continuous drain current, and operate across the full -55°C to 175°C temperature range. The HUF75344P3 provides 8mOhm on-resistance matching the STP85NF55 specification, while the HUF75345P3 offers superior performance at 7mOhm. Both parts are actively manufactured and ROHS3 compliant. The HUF75339P3 is also acceptable, offering 12mOhm on-resistance with 200W power dissipation.
Secondary Substitutes (Active Status, Enhanced Ratings):
The AOT470 from Alpha & Omega Semiconductor provides enhanced voltage (75V) and current (100A) ratings while maintaining active production status. This part is suitable for applications requiring additional design margin. The HUF75332P3 is available for lower current applications requiring 60A capacity.
Compatibility Considerations:
The IPP80N06S207AKSA1 from Infineon matches the STP85NF55 electrical specifications precisely (55V, 80A, 6.6mOhm on-resistance) but is discontinued at DiGi Electronics. This part may be sourced from alternative distributors if inventory is available.
The AUIRF3205Z and AUIRF3305 from Infineon are not recommended for new designs. The AUIRF3205Z is marked "Not For New Designs" and the AUIRF3305 is obsolete, similar to the STP85NF55.
The FDP75N08A from onsemi is obsolete and has a reduced operating temperature maximum of 150°C compared to the STP85NF55 specification of 175°C.
The AOT2610L provides lower power dissipation (75W) and reduced current capacity (55A), making it suitable only for applications with reduced thermal or current requirements.
Compliance and Regulatory Status:
All recommended substitute parts maintain ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements for electronic component procurement.
Frequently Asked Questions (FAQ)
Q: Can the HUF75344P3 directly replace the STP85NF55 without circuit modifications?
A: Yes. The HUF75344P3 maintains identical voltage (55V), current (75A minimum vs. 80A), on-resistance (8mOhm), gate threshold (4V), and operating temperature range (-55°C to 175°C). The TO-220-3 package is mechanically and electrically compatible. No circuit modifications are required.
Q: What is the difference between HUF75344P3 and HUF75345P3?
A: Both parts are rated for 55V and 75A continuous drain current. The HUF75345P3 has lower on-resistance (7mOhm vs. 8mOhm) and higher power dissipation capability (325W vs. 285W). The HUF75345P3 provides superior thermal performance and efficiency. Selection depends on application thermal requirements.
Q: Why is the AOT470 rated for 75V instead of 55V?
A: The AOT470 is a higher voltage-rated device (75V vs. 55V). This provides additional voltage margin in applications but does not affect compatibility with 55V-rated circuits. The higher voltage rating is a design enhancement, not a limitation.
Q: Is the IPP80N06S207AKSA1 a suitable replacement?
A: The IPP80N06S207AKSA1 matches the STP85NF55 electrical specifications exactly (55V, 80A, 6.6mOhm on-resistance). However, this part is discontinued at DiGi Electronics. It may be sourced from alternative distributors if inventory is available, but active production parts are preferred for long-term supply assurance.
Q: What is the significance of the TO-220-3 package designation?
A: TO-220-3 is a three-lead through-hole package with standardized pin spacing and thermal characteristics. All substitute parts listed use this package, ensuring mechanical compatibility with existing PCB layouts, heatsink mounting interfaces, and thermal management solutions.
Q: Can I use the AOT2610L as a direct replacement?
A: The AOT2610L is not recommended as a direct replacement. While it maintains 55V+ voltage rating and TO-220-3 packaging, it is rated for only 55A continuous drain current (vs. 80A) and 75W power dissipation (vs. 300W). This part is suitable only for applications with reduced current and thermal requirements.
Q: Why are AUIRF3205Z and AUIRF3305 not recommended?
A: The AUIRF3205Z is marked "Not For New Designs" and the AUIRF3305 is obsolete. While both parts are electrically compatible, they do not provide a path to long-term supply continuity. Active production alternatives such as HUF75344P3 and HUF75345P3 are preferred.
Q: Does the FDP75N08A have any limitations compared to the STP85NF55?
A: Yes. The FDP75N08A has a maximum operating temperature of 150°C, compared to 175°C for the STP85NF55. This 25°C reduction in maximum junction temperature may affect thermal margin in high-temperature applications. Additionally, the FDP75N08A is obsolete.
Q: What parameters should I verify when selecting a substitute part?
A: Verify the following parameters match or exceed the STP85NF55 specification: Vdss (55V minimum), continuous drain current Id (80A minimum), on-resistance Rds On (within application tolerance), gate threshold Vgs(th) (4V nominal), operating temperature range (-55°C to 175°C), and package type (TO-220-3). Confirm active production status or adequate inventory availability.
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